Multiple growths of high-entropy alloy nanostructures for energy conversion

• Main Author: Du, Tri Quang
• Other Authors: Huang Yizhong
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials::Nanostructured materials; Engineering::Materials::Functional materials
• Online Access: https://hdl.handle.net/10356/169176
• Institution: Nanyang Technological University

The energy predicament and environmental issues are the foremost challenges to mankind, drawing the world’s attention to develop renewable and sustainable energy sources with follow-up technologies, which can convert and store clean energy sources hydro power, wind power, or solar energy into fuel cells, advanced batteries, and solar cells. One of the most promising technologies is water splitting to generate green hydrogen fuels by electricity from renewable energy sources to make a complete cycle of clean energy. The emergence of renewable energy has gained significant interest in not only developing more potential functional materials but also the fabrication of advanced catalysts that meet the affordability and stability requirements for conventional energy conversion and storage. High-entropy materials have come into sight of academic literature, escalating their understanding and applications over a broad range of applications including aerospace mechanical and structures, anti-corrosion, thermodynamic protection, and especially electrocatalysis for renewable energy. New catalyst materials can be engineered to have the higher surface area and unique crystal structure by composing multiple elements from abundant and low-cost transition metals to form non-precious metal high-entropy alloys (HEAs) and reduce the production cost to commercialize the plentiful and powerful resources of hydropower. This research reports a rapid, shape-designable, and scalable strategy to synthesize HEA electrocatalysts, by laser irradiating of the precursor metal-salt solutions loaded on the carbon fiber paper. The near-infrared (1064 nm) laser is tunable between continuous and pulsed modes to provide not only HEA nanoparticles fabrication but also post-synthesis treatment. Multiple growths of HEA nanostructures by combining both laser irradiation modes, resulting in porous nanostructures embedded with defect-rich HEA nanoparticles. These structures enlarge the surface area and expose more active sites on the surface to boost the electrocatalytic performance. This work investigated oxygen evolution reaction (OER) of a remarkable electrocatalyst, made of multiple growths of CoCuFeMnNi high-entropy alloys on the carbon-fiber-paper substrate, served as a working electrode that can achieve 10 mAcm-2 with 277 mV of overpotential in 1 M KOH electrolyte for OER and remained stable functioning after over 15 hours. The formation of oxides, oxyhydroxides intermediates with synergetic surface metal active sites is predicted to escalate the oxygen evolution reaction. This research promotes an adaptable method for the cost-effective and efficient fabrication of high-entropy alloys to enhance water splitting and further energy conversion applications.